Polyamic acids, prepared by the reaction of dianhydrides (or trianhydrides) with diamines are typically prepared in high-boiling solvents such as diglyme or N-methylpyrrolidone. When used for coating purposes or for making film they are heated step-wise to 300.degree. C. to remove water of imidization and solvent. Certain poly(half-amides) particularly those containing polar groups, are very difficult to free of solvent because of their high polarity. Further, after heating at temperatures as high as 300.degree. C., films prepared from these systems tend to have significant numbers of bubbles or voids that are inimical to film quality.
It has been found unexpectedly, that when about 0.75 to about 5 mole percent of a polysiloxane are incorporated in polyamic acid backbone, the polyimide film formed can be more easily freed of solvent and water of imidization than a control film containing no polysiloxane.